In the manufacture of both fuel grade and anode-quality petroleum coke, a critical step is cutting the coke out of the coking drum (or oven). Conventional methods employ the use of two cutting bits: a pilot bit to drill a pilot or access hole through the coke, and a cutting bit for removing the remaining coke from the drum. This conventional method requires a minimum of two workmen to change over from the pilot bit to the cutting bit, is time consuming, and involves an element of risk from a safety standpoint since the workmen are required to manipulate (detach, slide apart, lift, slide together, attach) heavy pieces of equipment.
Some attempts to build a functional combination bit (i.e., a single bit capable of both drilling the pilot hole and the standard coke cutting) have met with limited success. One such attempt utilizes a spring to bias the flow controller to a first pilot position and pneumatic pressure to move the controller to a second cutting position. However, both the spring and the pneumatic valve are subject to plugging by the water-borne coke fines in the hydraulic operating fluid and in which the cutting bit is immersed. When the spring and/or valve become clogged, the cutting bit becomes wholly or partly inoperable. Further, because the flowpath for the hydraulic fluid in this tool creates turbulence, a 10% loss in hydraulic pressure results, with a corresponding loss in efficiency.
The present invention overcomes these difficulties by providing a combination bit that is manually operable to switch from a pilot mode to a cutting mode. This changeover can be accomplished by a single workman unbolting a nosepiece portion, rotating it through 90.degree. and rebolting it in place. This rotates an inner sleeve with two sets of flow ports from a first position where the first set of flow ports is aligned with the pilot nozzles to a second position where a second set of flow ports is aligned with the cutting nozzles. A stream diverter/divider positioned at the distal end of the combination bit's body provides optimum fluid transition to the cutting jets minimizing loss of fluid pressure and therefore maximizing efficiency. It should be noted that manual operable control means herein comprises an inner sleeve received within a cylindrical body portion, having a first plurality of flow ports for said first plurality of jet nozzles and a second plurality of flow ports for said second plurality of jet nozzles. The first and second plurality of flow ports alternatively provide fluid flow to said first plurality of said second plurality of jet nozzles, at the selection of an operator.
Various other features, characteristics and advantages of the present invention will become apparent after a reading of the following detailed description of the preferred embodiments.